A propeller shaft, also known as a drive shaft, delivers torque generated by a vehicle's engine to the vehicle's driven wheels. A key link in the delivery of torque to the vehicle's driven wheels is the connection between the propeller shaft and a pinion flange which is connected to the axle to which the driven wheels are mounted. When the propeller shaft rotates, it causes the pinion flange to rotate. When the pinion flange rotates, it delivers torque to the driven wheels.
Because the pinion flange and the propeller shaft do not remain continuously parallel with one another as the vehicle is operated, a U-joint is used to connect the propeller shaft to the pinion flange. U-joints are well known in the art. A conventional U-joint includes a cross member and four bearing cups. The cross member has four highly machined cylindrical protrusions. The four protrusions are arranged in the shape of a cross or a plus sign. The four bearing cups fit over the four protrusions and are designed to rotate about the protrusions, each pair of oppositely disposed bearing cups serving as an axis of rotation for the U-joint. Configured in this manner, a U-joint enables the transmission of torque from the propeller shaft to the pinion flange under circumstances where there is a non-zero angle between their respective longitudinal axes.
To connect the propeller shaft to the U-joint, a conventional propeller shaft is fitted with a weld yoke. The weld yoke has a pair of full-round receivers. Full-round receivers are one-piece structures that include circular openings that enable the weld yoke (or any other structure) to engage the pair of bearing cups for a full 360 degrees about its circumference. The full-round receivers of the weld yoke engage a first pair of bearing cups of the U-joint and therefore the propeller shaft is enabled to rotate about an axis formed by the first pair of bearing cups.
The second pair of oppositely disposed bearing cups conventionally engage receivers on the pinion flange. The pinion flange conventionally does not utilize full-round receivers. Rather, the pinion flange conventionally includes two semi-circular openings that are spaced apart and configured to receive the second pair of bearing cups. Once the second pair of bearing cups are seated in the semi-circular openings, semi-circular retainers are positioned over the second pair of bearing cups and fastened to the pinion flange, thereby attaching the second pair of bearing cups to the pinion flange. The fasteners used to attach the semi-circular retainers to the semi-circular openings are typically threaded fasteners that are inserted in the longitudinal direction of the pinion flange. With the semi-circular retainers attached in this manner, the pinion flange may now rotate about the axis formed by the second pair of bearing cups.
The longer the distance between the engine and the driven wheels, the longer the propeller shaft will need to be. The longer the propeller shaft is, the larger the diameter the propeller shaft will need to have in order to oppose the naturally occurring bending force that acts on the propeller shaft as it rotates. As the diameter of the propeller shaft increases, it encroaches on, and limits access to, the fasteners that secure the semi-circular retainers to the pinion flange. If the diameter of the propeller shaft is too large, there will either be insufficient access to the fasteners that retain the semi-circular retainers to the pinion flange or the weld yoke will need to be elongated and tapered to provide sufficient access to the fasteners that retain the semi-circular retainers to the pinion flange. Elongating and tapering the weld yoke, while being an adequate solution in most applications, leaves room for improvement. This is because the tapered shape of the weld yoke is less efficient at transmitting torque than is the tubular shape of the propeller shaft.
Accordingly, it is desirable to have an arrangement where the diameter of the propeller shaft is not limited by the need to preserve access to fasteners that secure the semi-circular retainer to the pinion flange. In addition, it is desirable to provide a more stable and robust engagement between the pinion flange and the second pair of bearing cups than is presently provided by the semi-circular receivers and the semi-circular retainers. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.